Method and apparatus for synchronizing of databases

ABSTRACT

A method for synchronizing a first database including first data records with a second database including second data records. The method includes starting a synchronization session with an electronic device on which the second database resides, requesting the first data records from the first database, temporarily disconnecting the synchronization session while awaiting receipt of the first data records, receiving the first data records, and restarting and completing the synchronization session.

FIELD

The present application relates generally to portable electronic devicesand to the synchronizing of data at a portable electronic device withdata embodied at a communication network.

BACKGROUND

Portable electronic devices such as wireless personal digital assistants(PDAs), smart telephones and laptop computers with wireless capabilitieshave gained widespread use for a variety of functions. Such devices arecommonly used for communication purposes including transportation ofdata, and run on a wide variety of networks from data-only networks suchas Mobitex and DataTAC to complex voice and data networks such asGSM/GPRS, CDMA, EDGE, UMTS AND W-CDMA networks.

These portable electronic devices commonly include databases for storingdata that is selectably retrievable by a user of a device. The dataforms a series of data records, each data record containing one or morefields. During operation of the device, the data is retrieved anddisplayed, or otherwise made available to the user. The data can bemodified, added to or deleted by the user of the device.

Advances in data storage have accompanied advances in portableelectronic devices, to provide for back-up of data stored at theelectronic device. By backing-up the device, data can be recovered inthe event of data loss at the electronic device. Various electronicdevices are backed-up by way of communication over a fixed (wire)connection between the electronic device and, for example, a computingstation such as a desktop computer. Once the data is stored in adatabase at the computing station, the stored data can be modified,added to or deleted by a user at the computing station.

Other portable electronic devices provide for back-up of data storedthereon to a computing station by way of a radio interface, using, forexample, the networks listed above. Thus, data is sent over a radiocommunication channel of a radio communication system, thereby forming acommunications link between the portable electronic device and a remotestation (a station not linked by wire communication). Again, once thedata is stored in a database at a computing station, the stored data canbe modified, added to or deleted at the computing station. Thus, whiledata stored in the database of the portable electronic device isbacked-up to a computing station, data is also transmitted from thecomputing station to the portable electronic device to synchronize thedatabases of the portable electronic device with the databases of thecomputing station. When a data record on a computing station does notexist on the portable electronic device, or when the content of the datarecord (the fields of the data record) of the computing station differsfrom the content of the corresponding data record of the portableelectronic device, then the additional data record or differing datarecord is transferred to the portable electronic device. Similarly, whena data record on a portable electronic device does not exist on thecomputing station, or when the content of the data record of theportable electronic device differs from the content of the correspondingdata record of the computing station, the additional data record ordiffering data record is transferred to the computing station. When adata record is deleted from the portable electronic device, a deletedata record indication is sent from the portable electronic device tothe computing station in order to delete the corresponding data recordat the computing station. Similarly, when a data record is deleted fromthe computing station, a delete data record indication is sent from thecomputing station to the portable electronic device in order to deletethe corresponding data record at the portable electronic device.

Data synchronization over a radio communication channel is clearlyadvantageous as data can be communicated remotely over large distances.Conventional manners of data synchronization over radio communicationchannels suffer disadvantages, however. When synchronization between aportable electronic device and a remote computing station is initiated,the portable electronic device sends information to the remote computingstation and then remains idle as it is engaged in the synchronizationprocess. After sending the information to the remote computing station,data flow from the portable electronic device is blocked while theportable electronic device awaits a response from the remote computingstation. While data flow from the portable electronic device is blocked,the remote computing station retrieves the records from the appropriatedatabases and determines what, if any, records are to be updated in thedatabases of either the portable electronic device or the remotecomputing station. In cases where there are many records that areretrieved or when several other portable electronic devices areperforming a synchronization with the same computing station, theportable electronic device, the retrieval of records from theappropriate databases and the determination of what records are to beupdated can take several minutes. Thus, the portable electronic deviceremains idle for several minutes while awaiting a response. Clearly along idle time negatively affects productivity and performance of theportable electronic device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram of a radio communication systemincluding a portable electronic device and a communication system havinga synchronization server according to one embodiment of the presentapplication;

FIG. 2 is a block diagram of certain internal components within theportable electronic device of FIG. 1;

FIG. 3 is a block diagram of certain internal components within thesynchronization server of FIG. 1;

FIG. 4 is a sequence diagram illustrating functions carried out at boththe portable electronic device and the communication system of FIG. 1during synchronization of databases connected by wireless interface;

FIG. 5, is a sequence diagram illustrating functions carried out at apersonal information management connector of the communication system ofFIG. 1;

FIG. 6 is a sequence diagram illustrating further functions carried outat both the portable electronic device and the communication system ofFIG. 1 during synchronization of databases connected by wirelessinterface; and

FIG. 7 is a sequence diagram illustrating further functions carried outat both the portable electronic device and the communication system ofFIG. 1 during synchronization of databases connected by wirelessinterface.

DETAILED DESCRIPTION OF THE EMBODIMENT

Reference is first made to FIG. 1 which shows a functional block diagramof a radio communication system indicated generally by the numeral 20.The radio communication system 20 provides for communications withportable electronic devices including the exemplary portable electronicdevice 22, as shown. The portable electronic device 22 and the radiocommunication system 20 are operable to effect communications over aradio communications channel therebetween. Data originating at theportable electronic device 22 is communicated to the radio communicationsystem 20 by way of the radio communications channel. Similarly, dataoriginating at the communication system 20 is communicated from theradio communication system 20 to the portable electronic device 22 byway of the radio communications channel, thereby providing data to theportable electronic device 22.

For the purposes of illustration, the communication system 20 isfunctionally represented in FIG. 1 and a single base station 24 isshown. The base station 24 defines a coverage area, or cell 26 withinwhich communications between the base station 24 and the portableelectronic device 22 can be effectuated. It will be appreciated that theportable electronic device 22 is movable within the cell 26 and can bemoved to coverage areas defined by other cells that are not illustratedin the present example. The communication system 20 includes a relaydevice 28 that is connected to the base station 24 and to asynchronization server 30. It will be understood that the functionsprovided by the relay device 28 and the synchronization server 30 can beembodied in the same device. The synchronization server 30 is connectedto an administration server 32, as shown. The administration server 32provides administrative services to the communications system 20 and,for instance, provides administrative control over the synchronizationserver 30.

The synchronization server 30 is also functionally coupled through apersonal information management connector 33 to databases, of which,three exemplary database types including databases 34, 36 and 38 areshown. The personal information management connector 33 interfacesbetween the synchronization server 30 and the databases 34, 36, 38. Itwill be understood that the personal information management connector 33is a functional component and can be provided by way of an applicationon the synchronization server 30. The databases of the present exampleare of a text format such as an Extensible Markup Language (XML) format.The data maintained in the databases 34, 36, 38, includes a number ofdata records, each data record containing a plurality of fields that arepopulated with data.

The portable electronic device 22, of which only particular functionalportions are shown in FIG. 1 for the purposes of the presentdescription, includes a plurality of databases 40, 42, 44 thatcorrespond to the databases 34, 36, 38, respectively, of thecommunication system 20. The databases 34, 36, 38 and the databases 40,42, 44, can be selectably altered in an asymmetrical manner such thatthe databases 34, 36, 38 of the communication system 20 do not match thedatabases 40, 42, 44 of the portable electronic device 22. In otherwords, any or all of the databases 34, 36, 38, 40, 42, 44 can be alteredby adding records, deleting records and modifying fields of the recordsby adding, deleting or modifying the data populating those fields.

Reference is now made to FIG. 2 which shows a block diagram of certaininternal components within the portable electronic device 22. Theportable electronic device 22 is based on a microcomputer that includesa processor 46 connected to a read-only-memory (ROM) 48 that contains aplurality of applications executable by the processor 46 to enable theportable electronic device 22 to perform certain functions includingsynchronization with the communication system 20. The processor 46 isalso connected to a random access memory unit (RAM) 50 and a persistentstorage device 52 which are responsible for various non-volatile storagefunctions of the portable electronic device 22 and in which thedatabases 40, 42, 44 are maintained. The processor 46 receives inputfrom input devices 54 such as a keyboard. The processor 46 outputs tooutput devices 56 such as an LCD display. The processor 46 is alsoconnected to an internal clock 58 and a radio device 60 which in turn isconnected to an antenna 61. Together the radio device 60 and the antenna61 are used to connect to the radio communication system 20 over a radiocommunications channel. Thus, the portable electronic device 22 isoperable to receive and transmit communication signals containing datathat is communicated to and from the communication system 20 via theradio device 60 and the antenna 61.

It will be understood that the functions described herein can be carriedout in any suitable manner. In the present example, the functions arecarried out by algorithms executable by the processor 46 in asynchronization application. For example, the processor 46 of theportable electronic device 22 is operable to perform hash functions byretrieving the data from one or more of the databases 40, 42, 44 of thepersistent storage device 52 and generating a hash, thereby placing theaccessed data in short-digest form. Hash functions performed by theprocessor 46 include, for example, computation of check sums as well asother hash function computations. The processor 46 is further operableto provide the generated hash to the radio device 60 for transmissionfrom the portable electronic device 22 to the radio communication system20 over the radio communications channel. Hash generation is triggeredeither by an input from the input device 54 or by a signal received fromcommunication system 20. The processor is further operable to generatean initiate session command and to transmit the command over the radiocommunications channel along with the hash. The portable electronicdevice 22 is operable to receive a temporary disconnect synchronizationsession command and to store synchronization session state informationin the RAM 50. The portable electronic device is further operable toreceive a restart synchronization session request and to restart thesynchronization session based on the session state information in theRAM 50.

The microcomputer of the portable electronic device 22 is operable toreceive communications from the communication system 20. For example,the microcomputer is operable to receive a request for additional hashinformation and in response, to provide additional hash information byretrieving data from one or more of the databases 40, 42, 44, performinghash functions on the data, thereby generating an additional hash andtransmitting the additional hash to the communication system 20. Themicrocomputer is further operable to receive a request for data recordswhich, in response to such a request, the data records are retrievedfrom one or more the databases 40, 42, 44 and transmitted to thecommunication system 20. Further still, the microcomputer is operable toreceive data transmitted from the communication system 20 and to writethe data by adding the data to one or more of the databases 40, 42, 44or overwriting data on one or more of the databases 40, 42, 44,maintained on the persistent storage device 52.

Reference is now made to FIG. 3 which shows a block diagram of certaininternal components within the synchronization server 30. Similar to theportable electronic device 22, the synchronization server 30 includes aprocessor 62 connected to a read only memory (ROM) 64 that includesapplications executable by the processor 62 and enables thesynchronization server 30 to perform certain functions includingsynchronization with the portable electronic device 22. The processor 62is also connected to a random access memory unit (RAM) 66 and apersistent storage device 68 which are responsible for variousnon-volatile storage functions of the synchronization server 30. Theprocessor 62 is functionally connected to the databases 34, 36, 38through the personal information management connector 33 and to therelay device 28, which in turn is connected to the base station 24 forconnecting to the portable electronic device 22 over a radiocommunications channel. Thus, the synchronization server 30 is operableto receive and transmit communication signals containing data that iscommunicated to and from the portable electronic device 22 via the relaydevice 28 and the base station 24.

Again, it will be understood that the functions described herein can becarried out in any suitable manner. In the present example, thefunctions are carried out by algorithms executable by the processor 62.For example, the processor 62 of the synchronization server 30 isoperable to receive communications generated by the portable electronicdevice relating to synchronization, including an initializesynchronization command and group hash values representing data fromdatabases of the portable electronic device 22. The synchronizationserver 30 is further operable to request data records from the personalinformation management connector 33 and to set a timer upon requestingthe data records from the personal information management connector 33,setting a period of time in which to receive a response to the request.The synchronization server 30 is further operable to generate adisconnect synchronization session command and to send the command viathe relay 28 and the base station 24 in the event that no response isreceived to the request within the period of time. The synchronizationserver 30 is operable to save synchronization session state informationand to generate a request to restart the synchronization session inresponse to receipt of a response to the request and to send the requestvia the relay 28 and the base station 24.

The synchronization server is operable to perform hash functions uponreceipt of the data from one or more of the databases 34, 36, 38 and togenerate a locally generated hash, thereby placing the accessed data inshort-digest form. The synchronization server 30 is further operable tocompare the hash information from the hash received from the portableelectronic device 22 to the hash information from the locally generatedhash. The synchronization server 30 is also operable to requestadditional information from the portable electronic device 22, based onand in response to results of the comparison of the hash informationfrom the hash generated by the portable electronic device 22 with thehash information from the locally generated hash. The request foradditional information is provided to the relay 28 and, through the basestation 24, is transmitted to the portable electronic device 22. Therequest for additional information can be a request for additional hashinformation or a request for data records, depending on the results ofthe comparison of the hash information from the hash generated by theportable electronic device 22 with the hash information from the locallygenerated hash. Further, the synchronization server 30 is operable toreceive data transmitted from the portable electronic device 22 (throughthe base station 24 and relay device 28) and to write the data by addingthe data through the personal information management connector 33, toone or more of the databases 34, 36, 38 or overwriting the data throughthe personal information management connector 33, on one or more of thedatabases 34, 36, 38. Further still, the synchronization server 30stores synchronization history data in the persistent storage device 68,thereby maintaining a listing of changes made to the databases 34, 36,38 connected through the personal information management connector 33 tothe synchronization server 30 and to the databases 40, 42, 44 of theportable electronic device 22. The synchronization server 30 accessesthe synchronization history data during synchronization operations toreduce the data communicated between the communication system 20 and theportable electronic device 22 in subsequent synchronizations bydetermining previously synchronized data.

Reference is now made to FIG. 4, which shows a sequence diagramillustrating functions carried out at both the portable electronicdevice 22 and the communication system 20 during synchronization ofdatabases connected by wireless interface, in accordance with oneembodiment of the present application. Coding of software for carryingout such steps is well within the scope of a person of ordinary skill inthe art. First, the portable electronic device 22 receives asynchronization trigger at 100, from, for example, a user input on theinput device 54, triggering a synchronization process for one of thedatabases 40, 42, 44. In the present example, synchronization istriggered for the database 40. In response to receipt of thesynchronization trigger, data is retrieved from the database 40 at step102 and the processor 46 first generates a record hash for each datarecord of the database 40 and then generates a group hash for thedatabase 40, based on the individual record hashes at step 104. Thus,the group hash is a hash representative of the data records of thedatabase 40. After generation of the group hash, an initialize commandis transmitted along with the group hash at step 106 to thecommunication system 20 over a radio communication channel. Theinitialize command initiates the synchronization process at thesynchronization server 30, identifies the database for synchronizationand provides synchronization session state information including asession state identifier. The portable electronic device 22 then awaitsa response from the communication system 20. While awaiting a response,the portable electronic device 22 remains idle as it is engaged in thesynchronization process. The response can be a termination of thesynchronization process in the event that all of the data records ofdatabase 40 are determined to match the data records of thecorresponding database at the communication system 20, a request forfurther information in the event of a mismatch, or a temporarysuspension of the synchronization process as further described below.

The communication system 20 receives the initialize command along withthe group hash at step 108 by receipt at the base station 24. The basestation 24 forwards the initialize command and the group hash to thesynchronization server 30. As indicated above, the initialize commandidentifies the database for synchronization and provides synchronizationsession state information including the session state identifier. Asynchronization session is thereby started with the portable electronicdevice 22. In response to receipt of the initialize command, thesynchronization server 30 generates a request at step 110 for all datarecords of the database on the communication system side 20 thatcorresponds with the database being synchronized on the portableelectronic device 22. In the present example, the database 34corresponds with the database 40 of the portable electronic device 22and thus, it is the records of the database 34 that are requested in therequest generated at step 110. The request is then sent to the personalinformation management connector 33 to retrieve the records of thedatabase 40 at step 112. Upon sending the request to the personalinformation management connector 33, the synchronization server 30 setsa timer at step 114. In the present example, the synchronization server30 sets a timer duration of 2 minutes for receiving a response from thepersonal information management connector 33.

Referring now to FIG. 5, which shows a sequence diagram illustratingfunctions carried out at the personal information management connector33 after a request is sent from the synchronization server 30. Coding ofsoftware for carrying out such steps is well within the scope of aperson of ordinary skill in the art. The request for all data records ofthe database 34 is received at the personal information managementconnector 33 at step 116. The personal information management connector33 then fetches all records from the database 34 in accordance with therequest, at step 118 and forwards the records to the synchronizationserver 30 at step 120. It will be appreciated that the time betweenreceiving the request at step 116 and sending the records to thesynchronization server at step 120 varies depending on a number offactors such as the number of data records in the database 34.

Reference is now made to FIG. 6 to describe further functions carriedout at both the portable electronic device 22 and the communicationsystem 20 during synchronization of databases connected by wirelessinterface. As indicated above, the synchronization server 30 sets atimer at step 114 (FIG. 4), after sending the request to the personalinformation management connector 33. At step 122, a response is receivedfrom the personal information management connector 33. In the presentexample, the response is received within the time period set by thetimer at step 114. Thus, the response is received within two minutes ofthe synchronization server 30 setting the timer and the timer ends. Theresponse from the personal information management connector 33 includesthe data records of the database 34.

At step 124 the processor 62 of the synchronization server 30 firstgenerates a record hash for each data record of the database 34. Therecord hashes are referred to herein as the locally generated recordhashes. From the locally generated record hashes, a group hash for thedatabase 34 is generated. Thus, the group hash is representative of thedata records of the database 34 and is referred to herein as the locallygenerated group hash. After generation of the locally generated grouphash, the hash information of the group hash received from the portableelectronic device 22 is compared with the hash information of thecorresponding locally generated group hash at step 126. If thecomparison of the hash information indicates that the database 40 of theportable electronic device 22 is not in mismatch with the respectivedatabase 34 of the communication system 20, then a response is sent tothe portable electronic device 22 to terminate the synchronizationsession at step 128.

The response is received at the portable electronic device 22 at step130 and the synchronization session is terminated at step 131.

If, on the other hand, the comparison of the hash information indicatesthat the database 40 of the portable electronic device 22 is in mismatchwith the respective database 34 of the communication system 20, then oneor both of the databases 34, 40 are to be updated and a request foradditional hash information is generated by the synchronization server30 at step 132. The request for additional hash information is a requestfor hash information associated with data records. The additional hashinformation is requested for each data record of the database 40 of theportable electronic device 22. After generation of the request foradditional hash information, the request is then transmitted at step 134to the portable electronic device 22.

Once the request for additional hash information is received at theportable electronic device 22 at step 136, each record hash generated atstep 104 is transmitted at step 142 to the communication system 20 overthe radio communication channel.

The additional hash information is received at the communication system20 and delivered to the synchronization server 30 at step 144. Inresponse to receipt of the requested additional hash information, eachhash received from the portable electronic device 22 is compared withthe corresponding additional locally generated hash (generated at step124) at step 148 and a determination is made as to whether any of thedata records of either or both the database 34 or the respectivedatabase 40 of the portable electronic device 22, has changed. For datarecords that are determined to match, the synchronization process endsat step 150 for those data records. For data records determined to be inmismatch, however, the comparison at step 148 also determines where thechange was made (i.e. at the communication system 20 side or at theportable electronic device 22 side). Thus, data records in which changeshave been made at one of the portable electronic device 22 and thecommunication system 20 that are not reflected in the corresponding datarecords at the other of the portable electronic device 22 and thecommunication system 20, are determined by the comparison at step 148.If it is determined at step 148 that the data has changed, the databasesare synchronized by updating the data records of the database 34 atcommunication system 20 or the respective database 40 at the portableelectronic device 22 or the databases 34, 40 at both the communicationsystem 20 and the portable electronic device 22 that are determined tobe mismatched at step 152. With the determination of a mismatch, aconflict resolution policy is run, thereby determining how themismatched data records are to be updated (i.e. whether to update thedatabase records on the portable electronic device 22 with the databaserecords of the synchronization server 30, whether to update the databaserecords of the synchronization server 30 with the database records onthe portable electronic device 22, or whether to update both).

Reference is now made to FIG. 7 to describe further functions carriedout at both the portable electronic device 22 and the communicationsystem 20 during synchronization of databases connected by wirelessinterface. As indicated above, the synchronization server 30 sets atimer at step 114 (FIG. 4) after sending the request to the personalinformation management connector 33. At step 154, the timer set at step114 expires. In the present example, no response is received within thetime period set by the timer at step 114. Thus, the timer expires andthe synchronization server 30 generates a response to the portableelectronic device 22 at step 156. In this case, the response includes atemporary disconnect command to temporarily suspend the currentsynchronization session. At step 158, the response is transmitted to theportable electronic device 22. The synchronization server 30 saves thegroup hash received from the portable electronic device 22 as well asthe synchronization session state information including the sessionstate identifier in the RAM 66 at step 160.

At step 162, the portable electronic device 22 receives the responseincluding the temporary disconnect command from the synchronizationserver 30. The portable electronic device 22 saves the synchronizationsession state information including the session state identifier in theRAM 50 at step 164 and the synchronization session is temporarilydisconnected at step 166. After disconnection of the synchronizationsession, other data that does not belong to the database 40 can be sentto and from the portable electronic device 22. Thus, the portableelectronic device 22 is no longer idle.

When a response is received from the personal information managementconnector 33, at the synchronization server 30, the synchronizationserver 30 then restarts the synchronization session using theinformation stored in the RAM 66 of the synchronization server 30.Referring again to FIG. 6, the response is received from the personalinformation management connector thereby restarting the synchronizationsession at step 122 and the synchronization server 30 generates thelocally generated group hash as described above in relation to FIG. 6,step 124. After generation of the locally generated group hash, the hashinformation of the group hash received from the portable electronicdevice 22 is compared with the hash information of the correspondinglocally generated group hash at step 126. If the comparison of the hashinformation indicates that the database 40 of the portable electronicdevice 22 is not in mismatch with the respective database 34 of thecommunication system 20, then a response is sent to the portableelectronic device 22 to terminate the synchronization session at step128.

The response is received at the portable electronic device 22 at step130 and the synchronization session is terminated at step 131. Thus, thesynchronization session state information is no longer stored in the RAM50.

If, on the other hand, the comparison of the hash information indicatesthat the database 40 of the portable electronic device 22 is in mismatchwith the respective database 34 of the communication system 20, then oneor both of the databases 34, 40 are to be updated and a request isgenerated by the synchronization server 30 at step 132. In the presentexample, the request includes a restart session request to restart thesynchronization session based on the session state information stored inthe RAM 66 along with a request for additional hash informationassociated with data records. The additional hash information isrequested for each data record of the database 40 of the portableelectronic device 22. After generation of the request at step 132, therequest is then transmitted at step 134 to the portable electronicdevice 22.

Once the request is received at the portable electronic device 22 atstep 136, the portable electronic device restarts the synchronizationsession using the information included in the request and thesynchronization session state information stored in the RAM 50. Inaccordance with the request for additional hash information. Each recordhash generated at step 104 is transmitted at step 142 to thecommunication system 20 over the radio communication channel.

As described above, the additional hash information is received at thecommunication system 20 and delivered to the synchronization server 30at step 144. In response to receipt of the requested additional hashinformation, each hash received from the portable electronic device 22is compared with the corresponding additional locally generated hash atstep 148. A determination is made as to whether any of the data recordsof either or both the database 34 or the database 40 of the portableelectronic device 22, has changed. For data records that are determinedto match, no further steps are taken. For data records determined to bein mismatch, however, the comparison at step 148 also determines wherethe change was made (i.e. at the communication system 20 side or at theportable electronic device 22 side). Thus, data records in which changeshave been made at one of the portable electronic device 22 and thecommunication system 20 that are not reflected in the corresponding datarecords at the other of the portable electronic device 22 and thecommunication system 20, are determined by the comparison at step 148.If it is determined that the data has changed at step 148, the databasesare synchronized by updating the data records of the database 34 atcommunication system 20 or the database 40 at the portable electronicdevice 22 or the databases 34, 40 at both the communication system 20and the portable electronic device 22 that are determined to bemismatched at step 150. With the determination of a mismatch, a conflictresolution policy is run, thereby determining how the mismatched datarecords are to be updated (i.e. whether to update the database recordson the portable electronic device 22 with the database records of thesynchronization server 30 or vice versa or both). After updating of thedata records, a final response is sent to the portable electronic device22 to terminate the synchronization session at step 152.

The final response is received at the portable electronic device 22 atstep 130 and the synchronization session is terminated at step 131.

According to one aspect there is provided a method for synchronizing afirst database including first data records with a second databaseincluding second data records. The method includes starting asynchronization session with an electronic device on which the seconddatabase resides, requesting the first data records from the firstdatabase, temporarily disconnecting a synchronization session whileawaiting receipt of the first data records, receiving the first datarecords, and restarting and completing the synchronization session.

Advantageously, when a portable electronic device awaits a response froma communication system during synchronizing, the synchronization sessionis temporarily disconnected allowing data flow from the portableelectronic device. In a particular aspect, a synchronization server setsa timer and if the data records have not yet been retrieved from theappropriate databases, the synchronization server sends a response tothe portable electronic device to temporarily disconnect thesynchronizing session. Thus, a limit is set for the time that theportable electronic device sits idle awaiting a response. When the datarecords are received by the synchronization server, a determination ofwhether or not records are to be updated is made and a message is sentto the portable electronic device to either terminate thesynchronization process if no records are to be updated on the portableelectronic device or to restart the synchronization session.

While the embodiment described herein is directed to a particularimplementation of the method and apparatus for synchronizing databasesconnected by wireless interface, it will be understood thatmodifications and variations to this embodiment are within the sphereand scope of the present application. For example, it will be understoodthat the portable electronic device 22 is not limited to three databasesas any suitable number of databases is possible. Similarly, thecommunication system 20 may include any suitable number of databases. Itwill also be understood that the steps described hereinabove are notlimited to the order in which they are described. The steps describedcan be performed in any suitable order as may occur to those skilled inthe art.

Many other modifications and variations may occur to those skilled inthe art. All such modifications and variations are believed to be withinthe sphere and scope of the present application.

1. A method of operating a synchronization server to synchronize a firstdatabase comprising first data records with a second database comprisingsecond data records, the method comprising: receiving, from a portableelectronic device on which said second database resides, an initializecommand to start a synchronization session between said portableelectronic device and said synchronization server, along with datarepresentative of said second data records; requesting said first datarecords from said first database, said first database not directlyaccessible by said portable electronic device; setting a timer uponrequesting said first data records; if said timer expires prior toreceiving said first data records, transmitting a response to saidportable electronic device which causes said portable electronic deviceto temporarily disconnect said synchronization sessions, wherebytransfer of data not belonging to said second database, to and from saidelectronic device, may occur; receiving said first data records;restarting and completing said synchronization session with saidportable electronic device after receiving said first data records; andotherwise, if said first data records are received prior to expiry ofsaid timer: completing said synchronization session with said electronicdevice.
 2. The method according to claim 1, wherein said restarting andcompleting said synchronization session comprises generating a requestat the synchronization server to restart the synchronization sessionafter receiving said first data records, sending said request to restartthe synchronization session to the portable electronic device andcompleting said synchronization session.
 3. The method according toclaim 1, wherein to temporarily disconnect said synchronization sessioncomprises saving synchronization session information.
 4. The methodaccording to claim 1 further comprising comparing informationrepresentative of said second data records with informationrepresentative of said first data records after receiving said firstdata records.
 5. The method according to claim 4, wherein completingsaid synchronization session comprises sending a response to theportable electronic device to terminate the synchronization session inthe event that the first data records match the second data records. 6.The method according to claim 4, wherein completing said synchronizationsession comprises sending a request for additional informationassociated with the second data records.
 7. The method according toclaim 6, further comprising: receiving said additional informationassociated with said second data records; comparing with additionalinformation associated with said first data records; and updating atleast one of said first data records and said second data records. 8.The method according to claim 7, wherein receiving informationrepresentative of said second data records comprises receiving a grouphash of said second data records.
 9. The method according to claim 7,further comprising generating a group hash of said first data recordsafter receiving said first data records and prior to said comparing. 10.The method according to claim 6, wherein said sending a request foradditional information associated with said second data recordscomprises sending a request for a record hash for each of said seconddata records.
 11. The method according to claim 10, wherein completingsaid synchronization session comprises: generating a record hash foreach of said first data records; comparing each record hash from saidfirst data records with a corresponding record hash from said seconddata records; and updating at least one of said first data records andsaid second data records.
 12. A computer-readable medium having computerreadable code embodied therein which is executable in a synchronizationsystem for controlling a synchronization server to synchronize a firstdatabase comprising first data records with a second database comprisingsecond data records, by: receiving, from a portable electronic device onwhich said second database resides, an initialize command to start asynchronization session between said portable electronic device and saidsynchronization server, along with data representative of said seconddata records; requesting said first data records from said firstdatabase, said first database not directly accessible by said portableelectronic device; setting a timer upon requesting said first datarecords; if said timer expires prior to receiving said first datarecords, transmitting a response to said portable electronic devicewhich causes said portable electronic device to temporarily disconnectsaid synchronization session, whereby transfer of data not belonging tosaid second database, to and from said electronic device, may occur;receiving said first data records; restarting and completing saidsynchronization session with said portable electronic device afterreceiving said first data records; and otherwise, if said first datarecords are received prior to expiry of said timer: completing saidsynchronization session with said electronic device.